Appropriate follow-up interval for biopsy confirmation of squamous intraepithelial lesions diagnosed by cervical smear cytology

Abstract

Correlation of gynecologic cytology and histology is a routine component of quality assurance in all cytology laboratories. However, the appropriate interval for histologic follow-up has not been studied. We analyzed all cases with a cytologic diagnosis of squamous intraepithelial lesion (SIL) during a 1-year period that had histologic follow-up within 1 year of cytologic sampling. Six hundred ninety-six Papanicolaou smears with 811 corresponding biopsy specimens were identified. Of the cytologic diagnoses of SIL, 68% were confirmed by biopsy. Biopsy specimens were obtained most often at two times, one at the time of cytologic diagnosis and another 40 days later. The ratio of biopsy specimens with a diagnosis of SIL to those without was highest during the first 60 days. Approximately 1% of diagnoses took almost 1 year to be confirmed. A follow-up interval of 100 days detected 78% of all SIL diagnoses yet still permitted time to affect subsequent patient treatment in most cases if desired. We conclude that for clinical purposes, the interval for histologic follow-up of a cytologic diagnosis of SIL should be less than 60 days, but for quality assurance purposes, the interval should be approximately 100 days.